How to change hostname on Linux

Edit /etc/sysconfig/network

First lets see what is in the file

$ cat /etc/sysconfig/network
NETWORKING=yes
HOSTNAME=localhost.localdomain
$

To change servers hostname to server12.hosthat.com, change the file as follows.

$ cat /etc/sysconfig/network
NETWORKING=yes
HOSTNAME=server12.hosthat.com
$

Now you need to reboot the server to change the hostname.